Question

Q 23 If x + y = 3, x^2 + y^2 = 5 then xy
is *​

Answer 1

Answer:

(x+y)^2 = (3)^2

x^2+y^2+2xy = 9

5 + 2xy = 9

2xy = 4

xy = 2

Answer 2

ANSWER

x+y = 3

we write it also , y = 3-x

x^2+y^2 = 5 ( given)

put the value of y in given

x^2+ (3-x)^2 = 5

x^2 + 9+ x^2 - 6x = 5

2x^2 - 6x = -4

2x^2-6x+4 = 0

on solving this equation we get ,

x = 2 , x = 1

and , on putting this value in

x+y=3 we get ,when x =2 , y = 1

when x=1 , y = 2

so when x =2 , y = 1

xy = 2

when x=1 , y = 2

xy = 2

hence the value of xy is 2